Valve arrangement for air blast circuit breakers



March 19, 1957 o w 2,786,119

VALVE ARRANGEMENT FOR AIR BLAST CIRCUIT BREAKERS Filed Feb. 15, 1955 5 L I:::] 0 I/ 8 9 J c 2 2 0 f5 2/ I I 22 I6 /9 i 5 i 23 /s 17 IN VEN TOR.

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United Sitates Patent VALVE ARRANGEMENT FOR AIR BLAST CIRCUIT BREAKERS Haakon Forwald, Ludvika, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a Swedish corporation Application February 15, 1955, Serial No. 488,213

Claims priority, application Sweden February 17, 1954 3 Claims. (Cl. 200--148) The present invention relates to an arrangement in air blast circuit breakers, where the main breaking gap is arranged in a container, permanently filled with air, from which, when opening the circuit breaker, a flow of air passes across the breaking contacts. The invention concerns a valve arrangement, by which the time for the air escape can be controlled in a simple way, so that it will not be longer than absolutely necessary for the extinction of the arc. According to the invention, a separately operated outlet valve is arranged, which, when opened, allows the compressed air in the container to remove the movable contact to open position, said contact being provided with a valve member, which, when the contact comes into open position, again blocks the outlet for the compressed air. The escape of compressed air from the container can, therefore, only take place during the time from separating the contacts until the movable contact reaches its open end position. This latter time can, according to the invention, be regulated thereby that the movable contact is combined with a braking piston, which is movable in a cylinder, which is, over a throttling valve, in communication with the interior of the compressed air container.

The arrangement is most readily understood with reference to the accompanying drawing. On the drawing, 1 designates the compressed air container, which is filled with compressed air through a pipe line 2. In thewall of the compressed air container 21 leading-through insulator 3 is inserted, which carries the stationary contact 4 of the circuit breaker. The movable contact is formed as a cylinder 5, which is, at the lower end, provided with a bottom 6 carrying an arcing contact 7. The movable contact is on the outside provided with a collar 8 serving as a braking piston and is movable in the cylinder 9, which, over a throttling valve 10, is in communication with the space in the cylinder 1. In the collar 8, back valves 11 are arranged, and further there is a helical spring 12 in the cylinder 9, which spring serves to move the movable contact into contact with the stationary contact 4. In the cylinder 5, immediately adjacent to the bottom 6, there are openings 13. The bottom 6 serves as a valve member in a blocking valve, which is formed by this bottom and the tightening edge 14 in the bottom of the cylinder 15. Below the cylinder 15 there is a further cylinder 16, in the side wall of which there is an opening 17, which can be closed by a valve member 18 joined with a membrane 19 by means of a valve stem 20. 21 is a pipe line for delivery of operating air to 'the membrane 19. Furthermore there is a pipe line 22,

by which the space in the cylinder 15 is brought in communication with the space in the cylinder 16. This pipe line projects into the space in the cylinder 16 in such a manner that, when the valve member 18 is in its position to the left, it tightens against the end of said pipe line.

Patented Mar, 19, 1957 The arrangement acts in the following way:

When operating air is delivered through the pipe line 21, the membrane 19 is moved to the left, and the valve member 18 is then also moved to the left against the end of the pipe 22. As the space inside the cylinder 15 is hereby brought in communication with the external air, the pressure of the air in the cylinder 1 will act on the cylinder 5 and move it downwards, whereby a flow of air occurs through the cylinder 5 across the foot-point of the are at the upper end of the cylinder and out through the opening 13 and further out through the opening in the bottom of the cylinder 15 and the opening 17 in the side wall of the cylinder 16. When the cylinder 5 reaches its lowermost position, the bottom 6 is tightening forced against the edge 14 in the bottom of the cylinder 15 and prevents thereby a further escape of air from the container 1. The time, during which escape of air is to take place, is regulated by means of the throttling valve 10, which determines the speed, at which the piston 8 moves in the cylinder 9.

When the circuit breaker is to be closed again, the operating pipe line 21 is evacuated, and the membrane 19 is then moved to the right by the helical spring 23 in the space 16. The valve member 18 will then be forced against the edge of the opening 17 after having left the end of the pipe 22, so that compressed air can be transmitted from the space in the cylinder 15 through the pipe line 22 to the space in the cylinder 16. As the same pressure will prevail on the two sides of the bottom 6, the cylinder 6 will be moved upwards by the helical spring 12, until it comes in contact with the stationary contact 4. When the cylinder 5 moves back to contact with the stationary contact 4, the damping piston 8 is out of action, because the back valves 11 now allow free passage of compressed air from the container 1 into the cylinder 9.

I claim as my invention:

1. An air blast circuit breaker comprising a container for compressed air, main breaking contacts forming a main gap near an air outlet from said container, an air blast valve arranged downstreamwardly of said breaking gap, and a blocking valve arranged between said breaking gap and said air blast valve, said blocking valve having a valve member fixed to the movable contact of said breaking gap.

2. A circuit breaker according to claim 1, comprising means forming an air space, a passage for the delivery of compressed air from said container to said space, and means whereby the said air blast valve when in its open position simultaneously closes the said passage and serves to close the movable contact.

3. A circuit breaker according to claim 1, comprising a damping piston actuated by the air in the container and connected to the movable contact, a cylinder within which the piston moves, means for admitting compressed air to said cylinder from the said container, and a throttling valve to control the passage of air to said cylinder to move said piston.

References Cited in the file of this patent UNITED STATES PATENTS 

